Organic carbon oxidation state shapes fermentative methanogenic microbiomes and controls greenhouse gas fluxes.
Hu R, Aronson HS, Weaver ME, Price MN, LaRowe DE
Soil Health
The compost you dig into your vegetable bed — and whether it's woody and lignin-rich or leafy and sugary — influences how much methane your soil microbes produce and which microbial communities establish themselves beneath your feet.
Not all organic matter rots the same way. Researchers found that compounds loaded with hydrogen and carbon (think fats and waxes) break down slowly in oxygen-free environments and release lots of methane, while sugary or acidic compounds break down faster with less methane. The microbes doing the work also sort themselves by preference — slow-growing methane-producing teams dominate reduced carbon, while faster-growing fermenters prefer the oxidized stuff.
Key Findings
Organic compounds with more negative oxidation states produced significantly more methane per mole of carbon consumed, consistent with thermodynamic predictions.
Microbial communities fed reduced carbon had higher biodiversity, more syntrophic bacteria and methanogens, and fewer fermentative bacteria than those fed oxidized carbon.
Individual fermentative bacterial species showed genomically encoded preferences for specific carbon oxidation states, both in lab experiments and field data, with negative-NOSC specialists having longer predicted doubling times.
chevron_right Technical Summary
Scientists discovered that the chemical nature of organic matter in waterlogged soils determines how much methane is released and which microbes thrive. Carbon-rich, reduced compounds break down slowly but generate far more methane, meaning the type of organic matter in rice paddies and wetlands directly controls how much of this potent greenhouse gas reaches the atmosphere.
Abstract Preview
Organic compounds with a negative nominal oxidation state of carbon (NOSC) are thermodynamically recalcitrant in anaerobic ecosystems, but few studies have measured the influence of NOSC on carbon ...
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